三向预应力混凝土箱梁桥拓宽改造箱梁翼缘板连接结构研究

Study of Connection Details of Box Girder Flanges in Widening of Three-Way Prestressed Concrete Box Girder Bridge

为解决三向预应力混凝土连续箱梁桥拓宽时的拼接难题,提出一种适用于箱梁翼缘板横向拼接的嵌入式钢板连接结构,以京沪高速公路盐河大桥为背景进行研究。采用MIDAS FEA软件建立全桥有限元模型,分析该结构在混凝土收缩徐变差、基础沉降差、车道荷载作用下的结构响应、横向传力机理,并对若干影响参数进行敏感性分析。结果表明:该连接结构能够形成横向传力通道,有效吸收新、旧桥间发生的纵向变形差异作用,满足横向拼接需要,结构可行;嵌入式钢板通过区域应力状态的连续改变完成了内力横向传递;嵌入式钢板厚度、布置间距、拼接缝宽度对钢板的应力影响明显,而钢板宽度对其影响相对较小。

When the three-way prestressed concrete continuous box girder bridge is widened,the connection of the old and new structures remains a problem.A connection realized by embedding steel plates that is applicable for transverse splicing of box girder flanges is proposed,and the Yanhe River Bridge on Beijing-Shanghai Expressway is taken as the background project for the study.The software MIDAS FEA was used to build the finite element model of the full bridge,to analyze the structural response and transverse load transfer mechanism under the action of shrinkage and creep difference of new and old concrete,foundation settlement difference and vehicle loads.Parametric sensitivity of a variety of influential factors was analyzed.The results show that the connection details can form transverse load transfer passages,and therefore,effectively absorb the longitudinal deformation difference between the new and existing structures.Embedding steel plates can fulfill the requirements of transverse splicing and create a feasible way of connection.The embedded steel plates can transversely transfer the internal forces via the continual change of local stress condition.The thickness and spacing of embedded steel plates and width of the splicing joint have significant influence on the stresses in the steel plates,but the influence of width of steel plates is relatively minimal.